Space shuttle science shows how 1908 Tunguska explosion was caused by a comet
June 24, 2009
Trees felled by the Tunguska explosion. Credit: the Leonid Kulik Expedition.
The mysterious 1908 Tunguska explosion that leveled 830 square miles of Siberian forest was almost certainly caused by a comet entering the Earth's atmosphere, says new Cornell University research. The conclusion is supported by an unlikely source: the exhaust plume from the NASA space shuttle launched a century later.
The research, accepted for publication (June 24, 2009) by the journal Geophysical Research Letters, published by the American Geophysical Union, connects the two events by what followed each about a day later: brilliant, night-visible clouds, or noctilucent clouds, that are made up of ice particles and only form at very high altitudes and in extremely cold temperatures.
"It's almost like putting together a 100-year-old murder mystery," said Michael Kelley, the James A. Friend Family Distinguished Professor of Engineering at Cornell who led the research team. "The evidence is pretty strong that the Earth was hit by a comet in 1908." Previous speculation had ranged from comets to meteors.
The researchers contend that the massive amount of water vapor spewed into the atmosphere by the comet's icy nucleus was caught up in swirling eddies with tremendous energy by a process called two-dimensional turbulence, which explains why the noctilucent clouds formed a day later many thousands of miles away.
Noctilucent clouds are the Earth's highest clouds, forming naturally in the mesosphere at about 55 miles over the polar regions during the summer months when the mesosphere is around minus 180 degrees Fahrenheit (minus 117 degrees Celsius).
The space shuttle exhaust plume, the researchers say, resembled the comet's action.
A single space shuttle flight injects 300 metric tons of water vapor into the Earth's thermosphere, and the water particles have been found to travel to the Arctic and Antarctic regions, where they form the clouds after settling into the mesosphere.
Kelley and collaborators saw the noctilucent cloud phenomenon days after the space shuttle Endeavour (STS-118) launched on Aug. 8, 2007. Similar cloud formations had been observed following launches in 1997 and 2003.
Following the 1908 explosion, known as the
Tunguska Event, the night skies shone brightly for several days across Europe, particularly Great Britain -- more than 3,000 miles away.
Kelley said he became intrigued by the historical eyewitness accounts of the aftermath, and concluded that the bright skies must have been the result of noctilucent clouds. The comet would have started to break up at about the same altitude as the release of the exhaust plume from the space shuttle following launch. In both cases, water vapor was injected into the atmosphere.
The scientists have attempted to answer how this water vapor traveled so far without scattering and diffusing, as conventional physics would predict.
"There is a mean transport of this material for tens of thousands of kilometers in a very short time, and there is no model that predicts that," Kelley said. "It's totally new and unexpected physics."
This "new" physics, the researchers contend, is tied up in counter-rotating eddies with extreme energy. Once the water vapor got caught up in these eddies, the water traveled very quickly -- close to 300 feet per second.
Scientists have long tried to study the wind structure in these upper regions of the atmosphere, which is difficult to do by such traditional means as sounding rockets, balloon launches and satellites, explained Charlie Seyler, Cornell professor of electrical engineering and paper co-author.
"Our observations show that current understanding of the mesosphere-lower thermosphere region is quite poor," Seyler said. The thermosphere is the layer of the atmosphere above the mesosphere.
More information: The paper is available at: http://www.agu.org/journals/gl/papersinpress.shtml
Feb 08, 2010
I think I may have heard something once about a theoretical weapon that would basically drop very large rods of metal from a "weaponized" satellite, to try and achieve something like this.
Details
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The energy released from the impact of a comet is 1/2mv^2 (half m v squared). The relative velocity of the comet to the earth is very high. Then you square it and you get a big number. Then multiply it by its mass (in kg) and you quickly get energy of a magnitude comparible to kilo tons of TNT explosives i.e. small nuke.
Math
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Velocity of comet approx. =100,000 km/hr =28,000 m/s
(based on halleys comet)
Mass approx. = 10^14 kg
(based on Comet 9P/Tempel 1 aka "deep impact")
Energy = (28 x 10^17)^2 Joules
1 Megaton of TNT = 4 x 10^15 J
Energy = (700)^2 MegaTons TNT.
Biggest nuke tested (Tsar Bomb) approx = 100 megaton
i think a good analogy would be jumping out of a plane at 10,000 ft without a parachute into a lake. water flows around you when you swim right, yet its as hard as concrete when you hit it at terminal velocity.
in other words, even a liquid ball of water hurling into our atmosphere would likely have a similar effect.
defunct-yes at one point there was a proposal for a satellite weapon to launch rockets or even simple metal rods from space. however, its against international treaty and always will be until the "Federation" becomes reality on our planet :)
comments travel at some speed. This is tremendous amount of energy, and it has to be released upon entry/collision.
kinetic-energy weapons, rods from gods :http://www.popsci...rods-god
I'm with you guys on this one. These researchers are just saying they made a connection with some clouds.. that is all. They probably didn't even run any simulations to see if it could possible be a comet and what the size of it would need to be to devastate such a large area. In the end, the only thing to be gleamed from this article is that the researches believe there was a large amount of water involved in the event, that is all.
Ricochet writes:
The energy released from the impact of a comet is 1/2mv^2 (half m v squared). The relative velocity of the comet to the earth is very high. Then you square it and you get a big number. Then multiply it by its mass (in kg) and you quickly get energy of a magnitude comparible to kilo tons of TNT explosives i.e. small nuke.
This does not even come into play because the solid object (comet) never impacted the terrestrial surface but rather exploded some distance above it's likely landing spot if it were an asteroid. We know this because the Russian study provided evidence that with intense damage to the landscape, but no crater was found. So what caused the multi megatonne explosion? Embedded in the ice crystals and in the crystalline silicate gains the comet contained highly explosive volatile gases such as methane which ignited under the intense pressure from atmospheric entry. All of the gas gas bubble ignited almost simultaneously in a chain reaction causing a massive explosion; displacement of huge volumes of air and micro crystalline cometary particles which felled the forest.
You can see what crystalline cometary grains look like at this link.
http://www.bccmet...ge4.html
Stellar grains here.
http://www.bccmet...ge3.html
I suppose you believe that getting hit by a frozen turkey does more damage than getting hit by a thawed one.
Actually, that was Googleplex that wrote that...
Just guessing, but I would think that observers then would find even a small increase in "brightness" significant - much less, perhaps, than we can see nowadays without instrumentation.